The present invention relates to a two-way curable silicone rubber composition or, more particularly, to a silicone rubber composition which is curable at room temperature by the irradiation with ultraviolet light or by the interaction with atmospheric moisture and useful as an adhesive or a sealing or caulking material.
There are known several types of room temperature curable silicone rubber compositions including those stable under a hermetically sealed condition but curable by the interaction with atmospheric moisture to give a cured silicone rubber and those curable by the irradiation with ultraviolet light. Compositions curable by different mechanisms for the crosslink formation are known and practically used among these classes of the silicone rubber compositions.
Each of these conventional room temperature curable silicone rubber compositions, however, has its own advantages and disadvantages. For example, A moisture-curable silicone rubber composition usually takes a considerably long time for complete curing or even for curing in the surface layer only which cannot be tack-free within a short time of several minutes or so because the curing thereof solely depends on the diffusion of the atmospheric moisture from the surface through the layer so that the room temperature curable silicone rubber compositions of this type cannot be used as an adhesive and sealing or caulking material of which curing within a short time is desired. The ultraviolet-curable silicone rubber compositions, on the other hand, have disadvantages that, although they are advantageous in respect of the rapid curing in the portion under direct irradiation with ultraviolet light, no curing of the composition is effected in the shaded portion or in the inner portion of a body formed of a composition colored with a pigment. When the layer of the composition has a relatively large thickness, in particular, curing is obtained only in the surface layer and the composition is left uncured in the depth of the layer scarcely reached by the ultraviolet.